Radiative Capture ofsElectrons in the Decay ofBe7

Abstract

The high-energy portion of the spectrum of internal-bremsstrahlung photons accompanying the allowed electron-capture transition from /sup 51/Cr to the ground state of /sup 51/V has been measured with a Ge(Li) gamma -ray spectrometer supplied with a pileup rejector. The most important correction for the residual pileup spectrum caused by the 320.1 kev nuclear gamma rays from the deexcitation of the first excited state in /sup 51/V was performed by extrapolation from a set of measurements with sources of different activities. The pulse-height spectrum of intenal-bremsstrahlung photons was corrected for detector response. For energies higher than 348.1 keV the number of bremsstrahlung photons emitted per ground-state electron-capture (EC) decay of / sup 51/Cr was determined to be (9.56 plus or minus 0.60) x l0/sup -5/. Corresponding theoretical values are 9.49 x l0/sup -5/ predicted by the theory of Martin and Galuber, and 9.47 x l0/sup -5/ deduced from recent calculations of Intemann. The present result confirms the predictions of theory for railiative capture of ls + 2s orbital electrons, in contradiction to recent results on /sup 51/Cr and other EC decaying light nuclides, obtained mainly by bremsstrahlung- gamma -coincidence measurements. The transition energy of /sup 51/Cr was determined to be 760more » plus or minus 15 keV, in good agreement with accepted atomic mass differences. (auth)« less